Broadband traveling wave device having a logarithmically varying bidimensional interaction space

ABSTRACT

An annular electron beam interacts with a slow wave structure having a periodicity in a specified circumferential direction and a substantially logarithmically continuously scaled or periodic characteristic in a radial direction. The electron stream is translated along a helical path bounded by conical members emanating from a common point of origin and the interaction of the electrons and circuit waves is generally in a transverse reentrant direction with suitable spatial harmonics. Elements of both the &#39;&#39;&#39;&#39;O&#39;&#39;&#39;&#39; and &#39;&#39;&#39;&#39;M&#39;&#39;&#39;&#39; type electron stream interaction coexist with appropriate adjustments of the DC fields in the bidimensional interaction space. An extremely wide bandwidth of as high as a decade for microwave frequency amplifiers as well as oscillators in either the forward or backward wave modes is provided with the disclosed structure.

United States atent [72] Inventor John M. Osepchuk Concord, Mom.

[21] App]. No. 867,752

[22] Filed Oct. 20, 1969 [45] Patented Dec. 28, 1971 [7 3] Assignee Raytheon Company Lexington, Mass.

[54] BROADBAND TRAVELING WAVE DEVICE HAVING A LOGARITHMICALLY VARYING BIDIMENSIONAL INTERACTION SPACE 15 Claims, 11 Drawing Figs.

[51] Int." H0lj 25/34 [50] Field oISearch 3315/35,

[5 61 References Cited UNITED STATES PATENTS 3,548,246 12/1970 Thal, Jr. et al. SIS/3.5 3,305,751 2/1967 Brown 315/3951 X 6 AXlS OF SYMMETRYJ;

3,527,976 9/1970 Thal,Jr..... 3,324,341 6/1967 Epsztein ABSTRACT: An annular electron beam interacts with a slow wave structure having a periodicity in a specified circumferential direction and a substantially logarithmically continuously scaled or periodic characteristic in a radial direction. The electron stream is translated along a helical path bounded by conical members emanating from a common point of origin and the interaction of the electrons and circuit waves is generally in a transverse reentrant direction with suitable spatial harmonics. Elements of both the 0 and M" type electron stream interaction coexist with appropriate adjustments of the DC fields in the bidimensional interaction space. An extremely wide bandwidth of as high as a decade for microwave frequency amplifiers as well as oscillators in either the forward or backward wave modes is provided with the disclosed structure.

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SHEET 1 BF 3 AXIS OF SYMMETRY BACKWARD RADIATION HIGH FREQUENCY 58 END all! I Nil LOW FREQUENCY z= END K NON-RADIATING ACTIVE RADIATING m CUT-OFF OR OSEPCHUK SLOW WAVE FAST WAVE EVANESCENT REGION REGION m m Fig. 3.

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sum 3 0F 3 CONICAL FEED LINE HIGH Q FREQUENCY END INTERACTION SPACE 33kg FREQUENCY END E mwivmk AXIS OF SYMMETRY JOHN M. OSEPCHUK Fig 11.

BROADBAND TRAVELING WAVE DEVICE HAVING A LOGARITHMICALLY VARYING BIDIMENSIONAL INTERACTION SPACE BACKGROUND OF THE INVENTION In the microwave art both traveling wave amplifiers as well as oscillators have evolved of the so-called linear or type or crossed field or M" type. Further, for many years crossedfield devices such as magnetrons, Amplitrons and Stabilotrons having reentrant type RF circuits and/or reentrant electron beams have also been employed for amplification and generation of high-frequency energy. All such prior art devices are limited, however, to relatively narrow bandwidths of operation and some devices such as klystrons may operate only at specific resonant frequencia. lllustratively, a -percent bandwidth is presently considered as the upper limit in the art for reentrant devices and an octave for nonreentrant devices. This bandwidth value indicates that a device operative at a center frequency of 5,000 megacycles could be tuned to approximately 500 megacycles either side of this frequency to set the lower and upper limits. The effective tuning range would then be 4,500-5,500 megacycles or 1,000 megacycles.

To ameliorate the foregoing disadvantages of the prior art numerous methods and devices have been introduced in the art. Notable amongst these are cascaded arrays of plural traveling wave devices each designed for a particular frequency or multiple of a preceding frequency. Hence, a broadband oscillator could feed a chain of amplifiers to cover a wide range of frequencies. Since changes in frequency require complete redesign of the electron beam-circuit interaction components, such traveling wave devices become rather costly, particularly at the higher frequencies where the com ponent parts are small. Such cascade arrangements may incorporate individual tube chains or plural periodic structures and electron beam generation means in a singular envelope.

A notable achievement in another field of art, namely, antenna and communications systems has arisen in recent years to handle a rather analogous situation. The limiting factors in the communication of electromagnetic energy using radiated wave propagation at all frequencies had been the narrow bandwidth due to the then known antenna parameters. The earlier structures were capable of frequency ranges from around an octave 2:1 up to 4:1. This art, however, received an impetus with the invention of the log periodic or equiangular antennas which are frequency independent. Broad bandwidths as high as :1 or on the average of the order of a decade or 10:1 were now possible in the communication field. An excellent summary of such broadband antenna configurations and the results accomplished may be had by referring to the article by E. J. Jordan et al. entitled Developments in broadband antennas I.E.E.E. Spectrum Apr. 1964, pages 58-71.

Suffice it to say, therefore, that on the one hand a substantially large segment of the electron tube art related to traveling wave devices is limited by narrow frequency bandwidths. On the other hand, a new and unique technique for broadband antenna and communications systems has evolved involving logarithmic principles. The adaptability of these concepts of periodicity to the traveling wave tube art, particularly at microwave frequencies, then, leads to the evolution of a new class of microwave energy devices having extremely broad frequency band capabilities.

SUMMARY OF THE INVENTION In accordance with the teachings of the present invention, a device is provided having a logarithmically varying bidimensional interaction space defined by conical bounding electrodes having the same point of origin including a periodic slow wave electromagnetic energy-propagating structure and an opposing substantially continuous conductive member. An electron beam generation source projects either a biconical or single conical annular stream of electrons circumferentially and radially translated to interact with the slow wave structure. The electron beam in the initial region is convergent and has a substantial cross-sectional dimension with accordingly higher intensity to result in higher average beam currents. Numerous embodiments of slow wave electromagnetic circuits may be employed including the plural vane type similar to magnetron crossed-field devices as well as interdigital or other periodic delay line structures. Strapping of alternate vanes similar to devices in the microwave magnetron art may also be practiced. Further, continuous scaled as well as log periodic circuit components are included within the concepts of the invention.

The conical annular electron beam possesses both 0" and M interaction characteristics which offers the advantage of utilization of both the electron potential energy as well as kinetic energy in the orthogonal DC fields for interaction with the AC electromagnetic field wave circuits. The electron stream orientation and electromagnetic propagation circuit, therefore, provides a generally transverse motion in a helical circumferential path which will be designated as 0 in ac cordance with well-known spherical coordinate designations as will be hereinafter explained. Additionally, there is a longitudinal translation component in the radial direction of the electron stream, however, the principal interaction is of the transverse reentrant type. The electric and magnetic fields bounding the bidimensional interaction space are oriented in such a manner that the E/B ratio throughout the interaction space length is substantially invariant in the logarithmically varying radial direction. The synchronous interaction of the beam and propagating wave velocities, as well as, even cyclotron mode synchronism can, therefore, be provided. The bidimensional configuration of the device provided by the invention leads to a periodicity in the 0 and r directions to result in suitable spatial harmonics for interaction in a reentrant manner with the electrons in the conical stream.

The electromagnetic wave propagation circuit is provided by segments defining substantially continuous tapered components in the radial direction as well as a conical geometry in the circumferential direction. At the base or widest portion of the circuit the low frequencies are generated while at the substantially smaller end approaching the apex of the conical configuration the higher frequencies are present. Appropriate means for input and output coupling in either the forward or backward wave modes of operation are connected to the electromagnetic circuit means in the conventional manner. The disclosed device provides in an integral structure a frequency bandwidth capability of substantially a decade or I02] and higher.

The high electron beam average powers will result in a higher output power capability in the resultant devices envisaged by the present invention. A class of devices can now be realized such as forward wave amplifiers or oscillators, backward wave oscillators or amplifiers, microwave rectifiers or accelerators having substantially high powers over extremely wide tuning ranges.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, as well as the details for the realization of a preferred embodiment, will be readily understood after consideration of the following detailed description and reference to the accompanying drawings, wherein:

FIG. 1 is an elevational view partly in section of the illustrative embodiment of the invention;

FIG. 2 is a diagrammatic representation of the spherical coordinates useful in the understanding of the invention;

FIG. 3 is a diagrammatic representation of a log periodic frequency independent antenna;

FIG. 4 is an elevational view partly in section of a portion of the embodiment shown in FIG. 1;

FIG. 5 is a cross-sectional view of the illustrative embodiment taken along the line 5-5 in FIG. 4;

FIG. 6 is a cross-sectional view taken along the line 66 in FIG. 4;

FIG. 7 is a cross-sectional view taken along the line 7-7 in FIG. 4;

FIG. 8 is a diagrammatic representation of the principle of the operation of the invention; 7

FIG. 9 is an elevational view of an alternative slow wave propagating structure of the log periodic type;

FIG. 10 is a cross-sectional view of another alternative slow wave structure of the interdigital periodic delay line type;

and FIG. 11 is a schematic representation of an alternative energy-feeding arrangement for the illustrative embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a biconical embodiment 2 of the invention is disclosed. In this configuration foursubstantially bounding conical segments having a substantially common point of origin are disposed to form an overall spherical assembly. Segments 4 and 6 are oppositely disposed and define the periodic slow wave delay line propagating circuits. An opposing electrode having a substantially smooth surface configuration similar to the sole electrode in M type crossed-field devices is provided by an integral segment comprising sections 8 and 10. The orientation of the respective segments having a common axis of symmetry provides for the bounding surfaces of substantially converging conical bidimensional interaction spaces 12 and 14. A common central crossover region 16 is thus provided for traversal by the electron stream. Interaction space 12 will direct the incoming converging electron stream and interaction space 14 directs the outgoing diverging conical stream. The interaction spaces thus provided have a tapered configuration logarithmically varying in a radial and circumferential direction. The slow wave propagating segments 4 and 6 may be in separate sections while the sole electrode defining segments 8 and 10 may also be provided as separate components united along a surface defined by dotted line 9.

A biconical annular electron stream emanates from, illustratively, an annular cathode gun assembly 18 of substantially large radius to provide an intense electron beam having a radia] as well as angular velocity through the interaction spaces. The cathode gun assembly 18 may be recessed within the sole electrode segment section 8. Appropriate adjustment of the DC field values as well as the initial electron stream launching conditions will provide the proper trajectories for the initially highly convergent type annular beam. Suitable leads 20 are provided for the cathode gun assembly. Specific details of the electron gun assembly such as emitter surfaces, heater and focusing electrodes have been omitted for the sake of clarity since they will follow well-known techniques in the art. In interaction space 14 the stream is of a divergent configuration after traversing the common crossover region 16. A grounded collector electrode 22 of an annular shape having a substantially large radius and tapered inner surface is provided at the end of the interaction space 14 to collect the electrons which remain after interaction with the wave periodically propagated along the slow wave circuits disposed on segments 4 and 6. Suitable means for mounting the collector electrode are provided in accordance with well-known construction and hence, have been purposely omitted. In the central or crossover region 16, the inwardly disposed ends of segments 4, 6, 8 and 10 have been shaped with a suitable surface to assist in the transfer of the electron beam from the first interaction space 12 to the second interaction space I4. The electron stream then, passes both conical interaction spaces through the appropriate electrode shaping as well as electric and magnetic field configurations. In the singular conical configuration the lower segment section 10 is omitted and the collector electrode or gun assembly may be disposed in the vicinity of the crossover region I6.

The device is rendered vacuum tight by means of envelope 30 surrounding the substantially spherical biconical structures. Suitable securing means such as brackets 32 may be utilized to position the envelope and hermetic seals provided by means such as heliarc welding may be utilized to fabricate the envelope. Exhaust means of the type well-known in the art will provide for the appropriate vacuum conditions within the envelope 30.

The illustrative embodiment shown in this view is an amplifier device and the energy to be amplified is fed to the delay line elements by conventional electromagnetic feed means 34 of the coaxial type having an inner conductor 36. The output energy may be coupled to a utilization load by coupling means 38 connected to a delay line element in segment 6 adjacent to the collector electrode 22. The details of the DC magnetic fields provided along the interaction spaces will be described in conjunction with views to be hereinafter described.

Referring now to FIG. 2, a diagrammatic representation of spherical coordinates is shown to assist in the explanation of the invention. A conical body member 40 has an axis of symmetry designated by the numeral 42. The inclined tapered surfaces of the conical body are designated by the numeral 44. The radius indicated by the symbol r then. extends in a direction from a point of origin such as the apex of the cone along the sides 44. The symbol q} is a measure of the angle of the conical side 44 from a reference plane such as horizontal line 46. Finally, the symbol 0 then designates the circumferential direction around the conical body member. The two coordinates which are of vital interest in the present application are the r and 6 designations.

In FIG. 3 some background material is shown relating to log periodic broadband antennas. The configuration illustrated is a simple dipole arrangement having a waveguide or coaxial transmission line feed 48 and plurality of dipole radiators 50. In a direction z the resonant or quasi-resonant elements or regions are indicated. In the first or high-frequency end of the radiating frequency band the elements are substantially close together with a progressively varying spacing and increasing lengths of the dipole radiators based on logarithmic calculations. In arriving at an analogy for a traveling wave tube device, the transfer of beam energy to circuit energy and vice versa will be similar to the radiation process of an antenna. At the end of the antenna where the radiator elements are the largest we find the low-frequency end of the band. The spacing between the dipole radiators is substantially larger than at the high-frequency end of the frequency band. Carrying the analogy stillfurther, the first section designated by the numeral 52 will function as a nonradiating slow wave region. The intermediate and next region 54 will be the active radiating or fast wave region while the final region will be referred to as the cutoff region 56. The radiation in the backward direction is indicated by the arrow 58 which is analogous to the backward wave modes in traveling wave devices.

It is noted that while the antenna elements are shown as discrete log periodic structures it is possible in the design of component parts to fabricate continuously scaled structures following the logarithmic calculations in arriving at the geometrical configuration. For simplicity in the discussion of the structure of a microwave device following these principles, the illustrations will deal mainly with the continuous scaled version bearing in mind that discrete log periodic elements are also\ within the teachings of the invention.

Referring now to FIG. 4, a portion of the embodiment as shown in FIG. 1 is illustrated. The slow wave delay line segment 4 has a generally conical peripheral surface 60 on which are supported a plurality of vane members 62. In accordance with the invention vane members 62 are of the continuous type and are tapered along the upper wall portion 64. It will be noted that the tapered configuration defines the interaction space 12 with the opposing sole electrode segment section member 8 having a conical tapered wall surface 66. Interaction space 14 will also be defined by surface 66 on segment section 10 and segment 6. An initially converging annular beam of electrons 68 is emitted from the electron gun assembly 18 which is recessed in the wall 66 of the sole electrode segment. The electron beam, by means of suitable optics, completely encompasses the segment 4 and the electrons preferably travel in a trajectory having both a radial as well as circumferential component. The crossover region 16 between the segments 4, 6, 8 and 10 is the point of maximum convergence of the beam and is also the high-frequency-generating end of the periodic delay line structures.

Referring to FIGS. 5-7, the overall orientation of the periodic slow wave delay line vane members 62 disposed on the surface 60 of segment 4 will be evident. The members have not been illustrated with alternate strapping of the type found in magnetron oscillators although they may be readily provided. In FIG. 5 or the low frequency (f, f,,) end of the overall tuning range the slow wave structure has a substantial radius of curvature and the vane members are substantially higher. A spacing 70, therefore, of substantially varying width results together with the variation in the height of the individual vane members along the interaction space. The electromagnetic wave circuit generated on the vane elements is alternately negative and positive for 11' mode interaction as indicated in the illustration. Interaction at other modes is possible but for simplicity only the 1r mode is described. As a result of the combination of the alternating wave currents and the substantially crossed electric and magnetic fields in the interaction space, a substantially spoke-type rotating space charge 72 is generated along a converging helical path. Interaction of the electrons with the electromagnetic wave circuits results when the transverse and longitudinal velocities are synchronous and yields the high-power energy in the applicable devices.

In linear or 0 type interaction the transfer of energy from electron to the traveling waves on the delay line circuit takes place when V, (electron drive -velocity) V,, (phase velocity). For M type interaction, however, the energy transfer is possible when V, g v In the devices under consideration both 0 and M" type interaction may be present.

In FIG; 6 the intermediate zone or what may be conveniently referred to as the center frequency f is shown. The vane members 62 are now spaced closer to define a narrower interaction space.

In FIG. 7 the high frequency end (fz fo) of the tuning band is shown and the spacing 76 between the respective vane members is substantially closer and they are substantially shorter. In the foregoing views the segment 4 has been shown as being hollow, however, a solid configuration will be equally suitable. Considerations of weight as well as expense would be involved in the final determination.

In the illustrative embodiment, referring again to FIG. 4 the magnetic circuit may preferably be provided by means of a plurality of helical coil windings 78 disposed in a tapered conical configuration within the hollow confines provided within the sole electrode segment sections 8 and 10. The resultant DC magnetic field will have both an r and a 0 component which will combine with the DC electric fields to influence the optics of the electron beam. Other appropriate magnetic field generation means such as rods, current carrying surfaces, or permanent magnets may be provided in lieu of the electromagnetic coils. The magnetic field is also bidimensional to serve in conjunction with the electric fields in controlling the bidimensional electron beam. The shaping of the magnetic field is therefore tapered in a logarithmic fashion matching the parameters of the bidimensional interaction spaces. The electric field is provided between the delay line circuit and the opposing sole electrode surfaces 66 by suitable means and is mutually perpendicular throughout the interaction path length to the magnetic field orientation. The axis of symmetry of the delay line segment as well as overall device configuration is indicated by the dotted line 80.

Referring now to FIG. 8, a diagrammatic representation of the interaction phenomenon inherent in the present invention will be described. The slow wave circuit is indicated generally by the numeral 82 and the opposing or sole electrode structure is designated 84. Circle 83 indicates the common point of origin of the conical members defining components 82 and 84. The sole electrode may be maintained at a negative DC potential while the slow wave circuit is positively DC biased to provide the appropriate electrical field in accordance with wellknown M" type crossed-field techniques. The biasing potentials may also be reversed. The magnetic field B mutually perpendicular to the electric field is indicated by the arrow 88.

The substantially radial translation of the electron beam is indicated by the curve in the interaction space 92 while the transverse component through the periodic slow wave structure is designated by the arrow 94 and symbol 0. Generally, the electrons drift at a velocity equal to the ratio of the electric field E. to the magnetic field B. This ratio in the present embodiment is maintained substantially invariant with the dimension r throughout the length of the interaction space.

The distance (it, represents the angle of the cone surface to the horizontal line 96 for the sole electrode segment 84 while the symbol indicates the angular deviation for the slow wave circuit from the same reference plane. The electric field then between electrode segments 82 and 84 may be represented by arrow 98 and has a value E d) with the direction being the difference between 4),, and (12 It is, therefore, noted that the biconical tapered electrode configurations measured from the common point of origin 83 provide a gun region designated r r while the beam reflection or crossover region is r r,. The so-called beam reflection region is designated by appropriate optics and electrode contouring so that the incoming electron stream is reflected into an outgoing electron stream in the opposite conical region. With the translation in the r direction of the electron stream to interact with the electromagnetic circuit energy there is a general transverse or 0 motion of the electron stream and the slow wave circuit propagation is reentrant in the direction. Elements of both the 0" and M type electron motion coexist in the biconical interaction spaces. The primary requirement then is a periodicity in the 0 direction to provide suitable spatial harmonics for reentrant interaction of the electrons with the circuit in the active region. The net amplified or generated energy flows in the radial or r direction. The input connections have been shown as being made at r r and may be in one or both regions d or d depending on whether the device is an amplifier or an oscillator.

The delay line slow wave propagating circuits are suitably terminated in accordance with conventional microwave art adjacent the inner region r r and in the outer region r r The slow wave delay line circuit has been illustrated as being of the continuously scaled embodiment with a taper in the r direction. As previously noted, the principles of the log periodic antenna may also be adapted to the slow wave circuit. Referring next to FIG. 9, an example of such a log periodic delay slow wave structure is illustrated. On a conically tapered segment member 100 similar to the segment member 4 in FIGS. 1 and 4, a plurality of discrete elements collectively define the periodic structures 102. At the high-frequency end of the tuning band members 104 and 106 separated by space 108 are of the shorter dimensions and spaced closer together similar to the antenna elements shown in FIG. 3 in the region 52. The intermediate frequencies of the slow wave delay line circuit are generated by members 110 and 112 of varying dimensions in height as well as spacing with openings 114 and 116 therebetween. Finally, at the low-frequency end of the tuning band the larger discrete elements are disposed consisting of members 118 and 120 with spaces 122 and 124 disposed therebetween. The periodic elements are all logarithmically designed to provide the bidimensional slow wave circuit.

In FIG. 10, still another alternative embodiment of a delay line circuit 126 is shown. In this embodiment an interdigital type of line is provided. Vane members 128 secured to the rods 130 define a space 132 therebetween. Additional vane members 134 extend within the spaces 132 and are supported by an annular ring 136. The ends of the vane members 128 are spaced from ring 136 and define a gap 138. A tortuous RF circuit path is, therefore, defined by the periodic structure with the same configuration as interdigital delay lines employed in conventional narrow frequency range traveling wave devices. The vane members 128 and 134 may be of the continuously scaled version or log periodic structures as desired and are bidimensionally variable in the direction r to provide a periodicity in the 0 direction for transverse reentrant interaction.

ln FIG. 11 an alternative electromagnetic energy feed is disclosed incorporating still further analogous structure involving in the logarithmic broadband antenna teachings. In this embodiment the high-frequency end of the tuning band is coupled to first, whereas in the former embodiments disclosed in F IG. 1 the low-frequency end was utilized. The tapered conical segment member 140 will support the slow wave delay line circuit. The opposing segment section member 142 defines the sole electrode with the bidimensional interaction space 144 provided therebetween. A coaxial feed line 146 which could also be of a spiral configuration is centrally disposed within the conical segment member 140 and terminates adjacent the end 148 of this member. The conical feed line then extends along the tapered surface of body member 140 as indicated at 150 and is in communication with the periodic delay line elements 152 by any convenient means such as slots or apertures. Each of the slots or apertures are structured to provide appropriate coupling to the periodic slow wave structure at all frequencies. The foregoing embodiment may also be utilized for the output section of the coupling means for the electromagnetic energy from the slow wave delay line circuit.

The invention thus disclosed has been described with reference to a particular illustrative embodiment. it is understood, of course, that other configurations of the slow wave delay line circuits as well as appurtenant structures may be varied, for example, to provide forward or backward wave modes of oscillation and/or amplification. Similarly, a single conical structure may be provided with the electron gun or collector electrodes disposed in the crossover or beam reflection" region. The numerous modifications, variations or alterations which may be practiced by those skilled in the art are considered to be within the spirit and scope of the invention as defined in the appended claims. lt is intended, therefore, that the foregoing description be considered as illustrative only and not in a limiting sense.

What is claimed is: 1. In combination: oppositely disposed electrode means bounding and defining therebetween an electron interaction space; said interaction space having a conical cross section of logarithmically varying bidimensional spatial characteristics; at least one of said bounding electrodes having means for propagation of electromagnetic wave energy adjacent to said space; means for the generation and direction of an annular electron beam through said interaction space; and means for establishing crossed electric and magnetic fields in said interaction space to yield a predetermined beam trajectory having transverse as well as longitudinal energy components; said electric and magnetic fields together with the fringing electric fields of said crossed propagated electromagnetic wave energy resulting in an electron space charge circumferentially and radially translated with respect to said propagation means in a velocity synchronous relationship where by a net flow of energy between the electrons and propagated waves is established in a radial direction over a substantially wide frequency range. 2. In combination: oppositely disposed electrode means bounding and defining therebetween an electron interaction space; said interaction space having a substantially conical tapered cross section dimensioned to provide logarithmically varying spatial characteristics; at least one of said bounding electrodes defining a periodic circuit for propagation of electromagnetic wave energy adjacent to said interaction space; means for the generation and direction of an annular electron beam through said space; and means for establishing crossed electric and magnetic fields in said interaction space to collectively provide with the fringing electric fields on said propagating circuit a substantially conical annular beam having transverse and ing:

oppositely disposed electrode means bounding and defining therebetween an electron interaction space;

said interaction space having a substantially conical tapered cross section dimensioned to provide logarithmically varying bidimensional spatial characteristics;

at least one of said bounding electrodes defining a periodic circuit for propagation of electromagnetic wave energy adjacent to said space;

means means for the generation and direction of an electron beam including an annular emitter member to initially provide a substantially convergent conical annular beam through said space;

and means for establishing crossed electric and magnetic fields in said interaction space to collectively provide with the fringing electric fields of wave energy on said propagating circuit a substantially logarithmically varying space charge having transverse as well as longitudinal energy components to interact circumferentially and radially with energy on said propagating circuit in a velocity synchronous relationship whereby a net flow of energy at the lower end of the frequency range is established where the propagating circuit and electron beam have the larger cross section and at the high end of the frequency range where the propagating circuit and electron beam have the smaller cross section.

4. A traveling wave device comprising:

oppositely disposed electrode means bounding and defining therebetween an electron interaction space;

said interaction space having a substantially conical tapered cross section dimensioned to provide logarithmically varying bidimensional spatial characteristics;

at least one of said bounding electrodes being of a substantially conical tapered configuration having an axis of symmetry and defining means for propagation of electromagnetic wave energy adjacent to said interaction space;

said electromagnetic wave energy propagation means including a plurality of slow wave delay line elements providing a substantially logarithmically varying tapered surface in a direction oriented angularly and radially with respect to said axis of symmetry and a periodic spaced structure oriented circumferentially with respect to said axis of symmetry; means for the generation and launching of an electron beam including an annular emitter member to initially provide a convergent conical annular beam through said space;

and means for establishing crossed electric and magnetic fields in said interaction space to collectively provide with the fringing electric fields of wave energy on said electromagnetic propagation means a substantially conical annular beam having transverse and longitudinal energy components to yield an electron space charge circumferentially and radially translated with respect to said propagation means in a velocity synchronous relationship with a net flow of energy between the electrons and propagated waves in a radial direction.

5. A traveling wave device according to claim 4 wherein said slow wave delay line elements define a substantially continuous tapered configuration.

6. A traveling wave device according to claim 4 wherein said slow wave delay line elements are provided in a spaced logarithmically varying configuration.

7. A traveling wave device according to claim 4 wherein means for the collection of electrons are provided at the terminal end of said interaction space.

8. A traveling wave device according to claim 4 wherein the ratio of said electric and magnetic fields is substantially invariant throughout the length of said logarithmically varying interaction space.

9. A traveling wave device according to claim 4 wherein the bounding electrode means opposite to said electromagnetic energy propagation means has a continuously tapered surface.

10. A biconical traveling wave device comprising:

oppositely disposed substantially tapered conical bounding electrode members having an axis of symmetry and defining a periodic electromagnetic wave energy propagation means;

plural substantially circumferentially disposed coextensive surfaces defining with said conical members and bounding therewith biconical electron interaction spaces intersecting at a common crossover region;

said interaction spaces having a cross section of logarithmically varying bidimensional spatial characteristics;

means for generation and launching of an annular electron beam having initially converging characteristics disposed adjacent to one end of said interaction spaces;

means for establishing crossed electric and magnetic fields in said interaction spaces to collectively provide with the fringing electric fields of electromagnetic waves on said propagation means a circumferentially and radially translated electron space charge of substantially converging configuration along the first interaction space adjacent to the beam generation means and substantially divergent characteristics after traversing said crossover region;

and said electrons interact in a velocity synchronous relationship with the waves on said propagation means whereby a net flow of energy is established in a radial direction over a substantially wide frequency range.

11. A biconical traveling wave device according to claim 10 wherein said electron beam generation means include an annular emitter member of substantially large cross section.

12. A biconical traveling wave device according to claim 10 and means at the terminal end of said interaction spaces for collecting said electrons.

13. A biconical traveling wave device according to claim 10 wherein said electromagnetic wave energy propagation means include slow wave delay line elements tapered in a logarithmically varying manner in a direction oriented angularly and radially with respect to said axis of symmetry.

14. A biconical traveling wave device according to claim 13 wherein said delay line elements are in a spaced logarithmically varying orientation.

15. A biconical traveling wave device according to claim 13 wherein said delay line elements define a continuous tapered surface.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.631.315 Dated December 28, 1971 Inventorfii) John M. Osepchuk It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 10, after "Amplitrons" insert M-- and after "Stabilotrons" insert Column 5, line 26, delete "drive" and insert drift Column 5', line 70, delete "electrical" and insert electric I Column 7, line 52, after "said" insert crossed Column 8, line 16, delete the first "means" Signed and sealed this 27th da of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM Do-1050 (10-69) uscoMM-oc B0376-P69 ".5. GOVERNMENT PRINTING OFFICE ISQ 0-356-334 

1. In combination: oppositely disposed electrode means bounding and defining therebetween an electron interaction space; said interaction space having a conical cross section of logarithmically varying bidimensional spatial characteristics; at least one of said bounding electrodes having means for propagation of electromagnetic wave energy adjacent to said space; means for the generation and direction of an annular electron beam through said interaction space; and means for establishing crossed electric and magnetic fields in said interaction space to yield a predetermined beam trajectory having transverse as well as longitudinal energy components; said electric and magnetic fields together with the fringing electric fields of said crossed propagated electromagnetic wave energy resulting in an electron space charge circumferentially and radially translated with respect to said propagation means in a velocity synchronous relationship where by a net flow of energy between the electrons and propagated waves is established in a radial direction over a substantially wide frequency range.
 2. In combination: oppositely disposed electrode means bounding and defining therebetween an electron interaction space; said interaction space having a substantially conical tapered cross section dimensioned to provide logarithmically varying spatial characteristics; at least one of said bounding electrodes defining a periodic circuit for propagation of electromagnetic wave energy adjacent to said interaction space; means for the generation and direction of an annular electron beam through said space; and means for establishing crossed electric and magnetic fields in said interaction space to collectively provide with the fringing electric fields on said propagating circuit a substantially conical annular beam having transverse and longitudinal energy components to yield a net flow of energy between the electrons and electromagnetic waves on said circuit when the phase velocity of said wave energy is in substantially synchronous relationship with the electron drift velocities.
 3. A broad frequency band traveling wave device comprising: oppositely disposed electrode means bounding and defining therebetween an electron interaction space; said interaction space having a substantially conical tapered cross section dimensioned to provide logarithmically varying bidimensional spatial characteristics; at least one of said bounding electrodes defining a periodic circuit for propagation of electromagnetic wave energy adjacent to said space; means means for the generation and direction of an electron beam including an annular emitter member to initially provide a substantially convergent conical annular beam through said space; and means for establishing crossed electric and magnetic fields in said interaction space to collectively provide with the fringing electric fields of wave energy on said propagating circuit a substantially logarithmically varying space charge having transverse as well as longitudinal energy components to interact circumferentially and radially with energy on said propagating circuit in a velocity synchronous relationship whereby a net flow of energy at the lower end of the frequency range is established where the propagating circuit and electron beam have the larger cross section and at the high end of the frequency range where the propagating circuit and electron beam have the smaller cross section.
 4. A traveling wave device comprising: oppositely disposed electrode means bounding and defining therebetween an electron interaction space; said interaction space having a substantially conical tapered cross section dimensioned to provide logarithmically varying bidimensional spatial characteristics; at least one of said bounding electrodes being of a substantially conical tapered configuration having an axis of symmetry and defining means for propagation of electromagnetic wave energy adjacent to said interaction space; said electromagnetic wave energy propagation means including a plurality of slow wave delay line elements providing a substantially logarithmically varying tapered surface in a direction oriented angularly and radially with respect to said axis of symmetry and a periodic spaced structure oriented circumferentially with respect to said axis of symmetry; means for the generation and launching of an electron beam including an annular emitter member to initially provide a convergent conical annular beam through said space; and means for establishing crossed electric and magnetic fields in said interaction space to collectively provide with the fringing electric fields of wave energy on said electromagnetic propagation means a substantially conical annular beam having transverse and longitudinal energy components to yield an electron space charge circumferentially and radially translated with respect to said propagation means in a velocity synchronous relationship with a net flow of energy between the electrons and propagated waves in a radial direction.
 5. A traveling wave device according to claim 4 wherein said slow wave delay line elements define a substantially continuous tapered configuration.
 6. A traveling wave device according to claim 4 wherein said slow wave delay line elements are provided in a spaced logarithmically varying configuration.
 7. A traveling wave device according to claim 4 wherein means for the collection of electrons are provided at the terminal end of said interaction space.
 8. A traveling wave device according to claim 4 wherein the ratio of said electric and magnetic fields is substantially invariant throughout the length of said logarithmically varying interaction space.
 9. A traveling wave device according to claim 4 wherein the bounding electrode means opposite to said electromagnetic energy propagation means has a continuously tapered surface.
 10. A biconical traveling wave device comprising: oppositely disposed substantially tapered conical bounding electrode members having an axis of symmetry and defining a periodic electromagnetic wave energy propagation means; plural substantially circumferentially disposed coextensive surfaces defining with said conical members and bounding therewith biconical electron interactiOn spaces intersecting at a common crossover region; said interaction spaces having a cross section of logarithmically varying bidimensional spatial characteristics; means for generation and launching of an annular electron beam having initially converging characteristics disposed adjacent to one end of said interaction spaces; means for establishing crossed electric and magnetic fields in said interaction spaces to collectively provide with the fringing electric fields of electromagnetic waves on said propagation means a circumferentially and radially translated electron space charge of substantially converging configuration along the first interaction space adjacent to the beam generation means and substantially divergent characteristics after traversing said crossover region; and said electrons interact in a velocity synchronous relationship with the waves on said propagation means whereby a net flow of energy is established in a radial direction over a substantially wide frequency range.
 11. A biconical traveling wave device according to claim 10 wherein said electron beam generation means include an annular emitter member of substantially large cross section.
 12. A biconical traveling wave device according to claim 10 and means at the terminal end of said interaction spaces for collecting said electrons.
 13. A biconical traveling wave device according to claim 10 wherein said electromagnetic wave energy propagation means include slow wave delay line elements tapered in a logarithmically varying manner in a direction oriented angularly and radially with respect to said axis of symmetry.
 14. A biconical traveling wave device according to claim 13 wherein said delay line elements are in a spaced logarithmically varying orientation.
 15. A biconical traveling wave device according to claim 13 wherein said delay line elements define a continuous tapered surface. 